Some conventional ultrasonic transducers, either piezoelectric or Capacitive Micromachined Ultrasonic Transducer (CMUT), are built on a bulky (e.g., greater than 500 μm thick) piece of silicon or other substrate and arranged in one-dimensional or two-dimensional arrays for medical imaging. Many of these conventional ultrasonic imagers are able to look in only one direction.
One exception to the above-described conventional transducers is the piezoelectric side-viewing imager used in Intravascular Ultrasonic Imagers (IVUS). This device includes a one-dimensional array of piezoelectric transducer mounted on the surface of a catheter to form a cylindrical array that can scan 360°. However, this piezoelectric transducer is limited to providing only two-dimensional images rather than real-time three-dimensional images as needed by many diagnostic processes.
Additionally, due to the difficulty of mounting multiple pieces of transducers on the front and the side of a catheter platform, commercial IVUS are typically equipped with either a side-looking imager or a front-looking imager, but not both.
Thus, it may be desirable to provide a miniature, monolithic ultrasonic imager having multi-direction-looking capabilities and the ability to provide real-time three-dimensional images.
Currently there is a commercially available ingestible capsule endoscope, called Pillcam, which uses a miniature CMOS camera hiding inside a plastic capsule to shoot color photographs of the gastrointestinal (GI) tract. As a minimally invasive device, Pillcam can be swallowed like a vitamin pill and can provide useful image information for diagnosing stomach or small-intestine disorders. Although Pillcam causes far less discomfort for the patient and can reach a much further extent than is capable by the traditional tube endoscope, it has three basic constraints. First, it can only see the surface of the gastrointestinal tract and can not see into the tissue. This limits its capability in determining the extent of a tumor or abnormality in the digestive organs. Secondly, Pillcam cannot shoot images of the colon or rectum because of blockage of stool. As a result, a colonscopy is need for diagnosing the disorders in the colon or rectum and the process is very discomfortable. Thirdly, Pillcam has only one camera and can only look at one direction when it (randomly) travels through the digestive tract. This could result in missing of critical images for a diagnosing process.
It may be desirable to provide an ingestible capsule endoscope that can provide imaging in more than one direction and/or an endoscope that can provide ultrasonic and visible light imaging.